Self-contained mechanical interlock having oppositely rotatable interlocking elements



Oct. 5, 1965 MARCO SELF-CONTAINED MECHANICAL INTERLOCK HAVING OPPOSITELY ROTATABLE INTERLOGKING ELEMENTS Filed July 9, 1963 4 Sheets-Sheet l INVENTOR. EEK/14985 flz/msveca 3,210,491 ITELY 4 Sheets-Sheet 2 B. D] MARCO SELF-CONTAINED MECHANICAL INTERLOCK HAVING OPPOS ROTATABLE INTERLOGKING ELEMENTS Oct. 5, 1965 Filed July 9. 1963 f/e 30a.

Oct. 5, 1965 B. DI MARCO 3,210,491

SELF-CONTAINED MECHANICAL INTERLOCK HAVING OPPOSITELY ROTATABLE INTERLOCKING ELEMENTS Filed July 9, 1965 4 Sheets-Sheet 4 l N VE N TOR. aW/v/Ma 0/ M4 760 United States Patent 3,210,491 SELF-CONTAINED MECHANICAL DITERLOCK HAVING OPPOSITELY ROTATABLE INTER- LOCKING ELEMENTS Bernard Di Marco, Lincoln Park, Mich, assignor to I-T-E Circuit Breaker Company, Philadelphia, Pa., a corporation of Pennsylvania Filed July 9, 1963, filer. No. 293,596 Claims. '(Cl. 200-50) This application is a continuation-in-part of my copending application Serial No. 264,325 filed Mar. 11, 1963 and now abandoned. This invention relates to motor starters in general and more particularly to a mechanical interlock which prevents the closure of one contactor when a second contactor is closed and prevents closure of the second contactor when the first contactor is closed.

In many applications it is necessary to provide two contactors connected to energize the same electrical device from the same energy source. Each contactor is arranged to energize the device in a different manner so that the device will perform under a different mode of operation. A typical application of this type is the control of a polyphase reversible rnotor.

For such application one contactor is arranged to energize the motor for forward rotation while the other contactor is arranged to energize the motor for reverse rotation. If both contactors were to be closed simultaneously, this would place a direct short on the power lines and severely damage one or both of the contactors.

In order to safeguard against this condition the prior art has provided numerous electrical and mechanical interlocks. This invention consists of a mechanical interlock of which is attachable between two contactors so as to be actuated directly by the contact carriers of the contactors.

The interlock of the instant invention is a selfcontained unit of especially simple construction enclosed in a tamper proof housing. The construction is such that only a minimum number of different parts is required. That is, in addition to the fastening rivets, all told only six parts are required and of these only three parts differ in construction from all the other parts.

Accordingly, a primary object of this invention is to provide a novel construction for a mechanical interlock to be utilized with contactors.

Another object is to provide an interlock of this type which is constructed as a tamper proof unit.

Still another object is to provide an interlock of this type whose construction requires a minimum number of different elements.

A further object is to provide an interlock of this type which may be mounted between two contactors without dismantling either of the contactors.

Another object of the invention is to provide an interlock wherein linear motion or the cooperating contactor carrier is imparted to the rotatable parts of the interlock by means of a freely rotatable roller.

A still further object is to provide an interlock of this type which is of economical construction and of reliable performance after many operations.

These as well as other objects of this invention shall become readily apparent after reading the following description of the accompanying drawings in which:

FIGURE 1 is a plan View illustrating the mechanical interlock of the instant invention operatively mounted between two contactors.

FIGURE 2 is a cross-section taken through line 2-2 of FIGURE 1 looking in the direction of arrows 2-2.

FIGURE 3 is an enlarged plan view of the interlock 3,210,491 Patented Oct. 5, 1965 ice with portions of the housings broken away to reveal certain internal elements.

FIGURE 4 is an enlarged end view of the interlock.

FIGURE 5 is an enlarged front elevation of the interlock with portions of the housing broken away to reveal certain internal elements.

FIGURE 6 is a side elevation showing the positions of the active interlock elements when one of the contactors is closed.

FIGURE 7 is a perspective of the interlock member which is moved by the contactor upon closing thereof.

FIGURE 8 is a bottom view of the interlock movable elements looking in the direction of arrows 8-8 of FIG- URE 5.

FIGURE 9 is a schematic of an electrical interlock arrangement.

FIGURE 10 is a side elevation showing a modified construction for the movable interlock member.

FIGURE 11 is an end view of the member of FIG- URE 10 looking in the direction of arrow 11, 11.

Now referring to the figures. FIGURE 1 illustrates mechanical interlock 20 of the instant invention operatively mounted between two identical contactors 21 and 22. Each of the contactors 21, 22 is of a type fully disclosed in the Cataldo et al. copending application, Serial No. 189,915, filed Apr. 24, 1962, entitled, Electrical Device, and assigned to the assignee of the instant invention. As will hereinafter become apparent, interlock 20 is constructed to prevent the closing of contactor 21 when contactor 22 is closed and is constructed to prevent closing of contactor 22 when contactor 21 is closed.

It is noted that mechanical interlock 20 may function alone or may be provided in addition to the electrical interlock arrangement illustrated in FIGURE 9. In FIG- URE 9 elements 21a and 22a are the operating coils of contactors 21 and 22, respectively. The energization of coil 21a operates the main circuit contacts of contactor 21 and also brings about the operation of auxiliary switch unit 23 which includes normally closed switch 23a and normally open switch 23b. Similarly, the energization of coil 22a brings about the operation of auxiliary switch unit 24 having normally closed switch 24a and normally open switch 24b.

One end of contactor coil 21a is connected through overload relays (not shown) to line L-2, while the other end of coil 21a is connected to stationary contact of normally open switch 23b and to contact 25a of normally open forward control 25. Contact 2512 of forward control 25 is connected to the arm of switch 231) and is also connected to the stationary contact of normally closed switch 24a. The arm of switch 24a is connected to normally closed stop control 26 and is connected through a jumper (not shown) to the stationary contact of normally closed switch 23a. The arm of switch 23a is connected to the stationary contact of normally open switch 24b whose arm is connected to contact 28a of normally open reverse control 28 and is also connected to one end of contactor operating coil 22a. The other end of coil 22a is connected through overload relays (not shown) to line L-2. The other contact 28b of reverse control 28 is connected to the juncture between switches 23a and 24b.

With the elements in the positions illustrated in FIG- URE 9 neither coil 21a nor coil 22a is energized. The momentary closing of forward control 25 completes a circuit from line L-2 through coil 21a, forward control 25, switch 24a and stop control 26 to line L-I. Energization of coil 21a opens switch 23a and closes switch 23b. Since the latter is in parallel with forward control 25, coil 21a will remain energized after release of forward control 25 until such time as stop control 26 is operated.

Thus, with coil 21a energized there is no circuit present for the energization of coil 22a even when reverse control 28 is closed.

With coil 21a denergized and reverse control 28 closed, the energizing path for coil 22a extends from line L-l through stop control 26, switch 23a, reverse control 28, coil 22a and overload relays (not shown) to line L-2. With coil 22a energized switch 24a is open thereby interrupting the energizing path for coil 21a. Siwtch 24b is now closed and since it is in parallel with reverse control 28 coils 22a remains energized after release of reverse control 28.

Now referring more particularly to FIGURES 1 and 2. It is seen that mechanical interlock 20 is a relatively thin unit mounted between contactors 21 and 22 with handles 31a and 31b of interlock 20 being positioned immediately below the contact carriers 29 of contactors 21 and 22, respectively. As fully explained in the aforesaid application, Serial No. 189,915, contact carrier 29 moves downward from the position illustrated in FIGURE 2 in order to bring about closing of the contactor main contacts. In moving downward with respect to FIGURE 2, contact carriers 29 of contactors 21 and 22 engage handles 31a and 31b of interlock 20, respectively, for a purpose which will be hereinafter explained.

Now referring more particularly to FIGURES 3 through 8. Mechanical interlock 20 is provided with a housing 35 constructed of two molded sections 35a and 35!) joined along line 350 and secured to one another by rivets 36. Each of the housing sections 35a and 3512 are of identical construction and are provided with formations which cooperate to define housing chamber 37 wherein the other elements of interlock 20 are mounted and a notch 99 wherein handles 31a and 3112 are movable.

Handles 31a and 3112 are integrally formed portions of operators 30a and 3012, respectively. Since these operators are of identical construction only one will be described it being undersoood that suffixes a will denote portions of operator 30a and suffixes b will denote like portions of operator 30b. In addition, other reference numerals which differ only in their sufi'lxes identify members of identical construction.

As most clearly seen in FIGURE 7, operator 30a includes main plate-like portion 37a with handle 31a being a cylindrical formation extending to the rear of plate 37a at one upper corner thereof. Integrally formed bearing pin 38a extends from the rear of plate 37a at the other upper corner thereof while spring locating formation 39a, coaxial with pin 38a, extends forward of plate 37a. Integrally formed plate-like blocking formation 40a is located on the front surface of plate 37a at the bottom thereof. Formation 40a includes rounded edge 41a whose upper end portion 42a constitutes a blocking tip, as will hereinafter become apparent.

Also extending forward from plate 37a is lug 43a which, as clearly seen in FIGURE 6, is engaged by one end of torsion spring 44a whose other end bears against lug 45a formed integrally with housing section 35a. Spring 44a is a coiled member wound about operator formation 39a. Housing section 35a is provided with a formation to receive pin 38a cooperating therewith to constitute a pivot for operator 30a. Thus, it is seen that spring 44a biases operator 30a in a counterclockvw'se direction wit-h respect to FIGURE to a position wherein edge 46a of plate 37a abuts internal surface 47a of housing section 3541. Similarly, torsion spring 44b biases operator 30b in a clockwise direction with respect to FIGURE 5 about pin 31b so that plate edge 46b abuts internal formation 47b of housing section 35b.

As seen in FIGURE 6, when contactor 22 is closed its contact carrier 29 engages handle 31b thereby moving it downward and by so doing causes operator 3% to rotate counterclockwise against the force of its biasing spring 4412 placing blocking tip 421) in the path of curved surface 410. Under these conditions, handle 31a can be moved downward only a negligible amount before surface 41a engages blocking tip 42b.

Thus, it is seen that with contactor 22 in closed position contactor 21 is mechanically prevented from closing by interlock 20.

Even though blocking tip 42b in the position of FIG- URE 6 essentially prevents movement of operator 30a, it is seen in FIGURE 5 that with contactors 21 and 22 open either of the operators 300 and 30b is free to be moved, since neither of the blocking tips 42a, 42b are opposite curved surfaces 41a, 4111.

It should be apparent that in the manner previously described the closing of contactor 21 will cause operator 30a to be operated in a clockwise direction with respect to FIGURE 5 thereby bringing its blocking tip 42a opposite surface 41b of operator 30b so that motion of operator 30b is blocked and contactor 22 is prevented from closing.

Surfaces 41a and 41b are curved to prevent jamming. That is, once a blocking tip is engaged the curved surface of the other operator, a camming action takes place which permits the blocking tip to continue to its end position (the end positon for blocking tip 42b is its position of FIGURE 6), thereby permitting one of the contactors to close. This is in contrast to many prior art devices of this type where both contactors jam in a position with their contacts moved toward engagement, but with neither contactor closed.

It is noted that the distance between blocking tip 42a and pivot pin 38a is far greater than the distance between handle 31a and pivot pin 38a. Thus movement of handle 31a appears as a magnified movement of blocking tip 42a.

Operator 30 illustrated in FIGURES 10 and 11 differs from operators 30a and 30b in that the former is provided with roller 81 which replaces handle 31a. For the sake of brevity a detailed description of operator 30' will not be given, it being apparent that the primed reference numerals of FIGURES 10 and 11 designate identical parts referred to in FIGURE 7 by numerals having the sufiix (a).

Roller 81 is secured to plate 37' by rivet 82 with shoulder 83 of rivet 82 bearing against 37 to position the rivet head so that roller 81 will not jam against plate 37. Roller 81 is constructed of nylon or other material dissimilar to the material of rivet 82 to reduce friction between these members.

Roller 81 provides improved operation by reducing friction between the contactor and interlock. That is, since contact carrier 29 moves linearly and handle 30a is pivoted as contact carrier 29 engages handle 30a, there is relative sliding motion between these members. In the case of handle 30a which is not free to rotate a friction resistance is established which causes wear and must be overcome by the operating force of the contactor. Since roller 81 is freely rotatable about rivet 82 resistance to sliding motion is substantially eliminated.

Thus, this invention provides a novel construction for a mechanical interlock. The interlock is provided with a housing so that the unit is tamper proof. Further, the construction is such that it is not necessary to dismantle either of the contactors utilized with the interlock in order to mount the interlock and still further only a minimum number of parts are required.

Although there has been described a preferred embodiment of this novel invention, many variations and modifications will now be apparent to those skilled in the art. Therefore, this invention is to be limited, not by the specific disclosure herein, but only by the appending claims.

The embodiments of the invention in which an exclusive privilege or property is claimed are defined as follows.

1. A mechanical interlock comprising a relatively thin housing having internal formations cooperating to define a chamber, a first and a second operator disposed in said chamber, each of said operators including a handle, said handles extending external of said housing from opposite faces thereof, each of said operators including a blocking formation, pivotal mounting means for said operators, biasing means urging said operators in opposite directions about said pivotal mounting means to first positions, said operators being independently operable in opposition to said biasing means to second positions by engagement with individual elements of cooperating contactors moving in the same direction, said operators positioned so that predetermined movement of either operator part way toward its second position places the blocking formation of this operator in the path of movement of the blocking formation of the other of said operators so that the latter is prevented from moving to its second position.

2. A mechanical interlock comprising a relatively thin housing having internal formations cooperating to define a chamber, a first and a second operator disposed in said chamber, each of said operators including a handle, said handles extending external of said housing from opposite faces thereof, each of said operators including a blocking formation, pivotal mounting means for said operators, said handles being located between said pivotal mounting means for said operators, biasing means urging said operators in opposite direction about said pivotal mounting means to first positions, said operators being independently operable in opposition to said biasing means to second positions by engagement with individual elements of cooperating contactors moving in the same direction, said operators positioned so that predetermined movement of either operator part way toward its second position places the blocking formation of this operator in the path of movement of the blocking formation of the other of said operators so that the latter is prevented from moving to its second position.

3. An interlock as in claim 2 in which each of said blocking formations includes a curved part having an end portion, said end portion of either one of said 0p erators being in blocking relationship opposite the curved part of the other of said operators for all positions of the respective operators between its said second position and its said predetermined movement part way toward its second position.

4. An interlock as in claim 3 in which the pivotal mounting means is comprised of pins individual to each of said operators and formed integrally therewith, for each of said operators said handle being positioned appreciably closer to said pin that the distance between said blocking formation and said pin.

5. A mechanical interlock comprising a relatively thin housing having internal formations cooperating to define a chamber, a first and a second operator disposed in said chamber, each of said operators including a handle, said handles extending external of said housing from opposite faces thereof, each of said operators including a blocking formation, pivotal mounting means for said operators, said handles being located between said pivotal mounting means for said operators, biasing means urging said operators in opposite directions about said pivotal mounting means to first positions, said operators being independently operable in opposition to said biasing means to second positions by engagement with individual elements of cooperating contactors moving in the same direction, said operators positioned so that predetermined movement of either operator part way toward its second position places the blocking formation of this operator in the path of movement of the blocking formation of the other of said operators so that the latter is prevented from moving to its second position, each of said handles comprising a freely rotatable roller.

References Cited by the Examiner UNITED STATES PATENTS 2,262,071 11/41 Valkenburg 200-98 X BERNARD A. GILHEANY, Primary Examiner. 

1. A MECHANICAL INTERLOCK COMPRISING A RELATIVELY THIN HOUSING HAVING INTERNAL FORMATIONS COOPERATING TO DEFINE A CHAMBER, A FIRST AND A SECOND OPERATOR DISPOSED IN SAID CHAMBER, EACH OF SAID OPERATORS INCLUDING A HANDLE, SAID HANDLES EXTENDING EXTERNAL OF SAID HOUSING FROM OPPOSITE FACES THEREOF, EACH OF SAID OPERATORS INCLUDING A BLOCKING FORMATION PIVOTAL MOUNTING MEANS FOR SAID OPERATORS, BIASING MEANS URGING SAID OPERATORS IN OPOPSITE DIRECTIONS ABOUT SAID PIVOTAL MOUNTING MEANS TO FIRST POSITIONS, SAID OPPERATORS BEING INDEPENDENTLY OPERABLE IN OPPOSITION TO SAID BIASING MEANS TO SECOND POSITIONS BY ENGAGEMENT WITH INDIVIDUAL ELEMENTS OF COOPERATING CONTACTORS MOVING IN THE SAME DIRECTION, SAID OPERATORS POSITIONED SO THAT PREDETERMINED MOVEMENT OF EITHER OPERATOR PART WAY TOWARD ITS SECOND POSITION PLACES THE BLOCKING INFORMATION OF THIS OPERATOR IN THE PATH OF MOVEMENT OF THE BLOCKING FORMATION OF THE OTHER OF SAID OPERATORS SO THAT THE LATTER IS PREVENTED FROM MOVING TO ITS SECOND POSITION. 